cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-5 of 5 results.

A113291 a(n) = A113290(n,1)/(n+1) for n>=0, where A113290 is the matrix log of triangle A113287.

Original entry on oeis.org

0, 0, 0, 1, -2, 4, -7, 13, -24, 48, -99, 221, -512, 1268, -3247, 8773, -24400, 70896, -211347, 653541, -2068472, 6755684, -22541135, 77305981, -270435640, 969413776, -3539893923, 13212871629, -50180362320, 194412817844, -765590169935, 3070433223317
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Crossrefs

Programs

  • PARI
    a(n)=if(n<3,0,(-1)^(n-3)*sum(k=0,n-3,sum(j=0,k\2,(k-j)!/(k-2*j)!)))

Formula

G.f. satisfies: A(x) = x^3*((2+x)/(1+x) + (1+x)*A'(x))/(2+3*x+2*x^2). a(n+3) = (-1)^n*Sum_{k=0..n} Sum{j=0..[k/2]} (k-j)!/(k-2*j)! for n>=0. a(n+3) = -a(n+2) + (-1)^n*A072374(n) for n>=1.

A113292 Column 0 of triangle A113290, which is the matrix log of A113287.

Original entry on oeis.org

0, 2, -3, 6, -10, 19, -35, 72, -150, 343, -803, 2024, -5226, 14299, -40027, 117392, -351798, 1095735, -3483403, 11442896, -38326586, 132070827, -463565299, 1668391912, -6110374070, 22885849335, -87147853011, 338645273368, -1336767522026, 5375276276699
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Crossrefs

A113287 Triangle T, read by rows, where row n of T equals row n of matrix (n+1)-th power of triangle A112555.

Original entry on oeis.org

1, 2, 1, -3, 0, 1, 4, 4, 4, 1, -5, -10, -10, 0, 1, 6, 18, 24, 12, 6, 1, -7, -28, -49, -42, -21, 0, 1, 8, 40, 88, 104, 72, 24, 8, 1, -9, -54, -144, -216, -198, -108, -36, 0, 1, 10, 70, 220, 400, 460, 340, 160, 40, 10, 1, -11, -88, -319, -682, -946, -880, -550, -220, -55, 0, 1
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Comments

Remarkably, the matrix logarithm (A113290) is an integer triangle. Matrix m-th power of A112555 = I + m*(A112555 - I) where I = identity matrix.

Examples

			Triangle begins:
1;
2,1;
-3,0,1;
4,4,4,1;
-5,-10,-10,0,1;
6,18,24,12,6,1;
-7,-28,-49,-42,-21,0,1;
8,40,88,104,72,24,8,1;
-9,-54,-144,-216,-198,-108,-36,0,1;
10,70,220,400,460,340,160,40,10,1; ...
		

Crossrefs

Cf. A112555, A113288 (inverse), A113290 (log), A113291, A072374.

Programs

  • PARI
    {T(n,k)=local(x=X+X*O(X^n),y=Y+Y*O(Y^k)); polcoeff(polcoeff(1/(1-x*y)+x*(x+2)/((1-x*y)^2*(1+x+x*y)^2),n,X),k,Y)}

Formula

G.f.: A(x, y) = 1/(1-x*y) + x*(x+2)/((1-x*y)^2*(1+x+x*y)^2).

A113288 Matrix inverse of triangle A113287.

Original entry on oeis.org

1, -2, 1, 3, 0, 1, -8, -4, -4, 1, 15, 10, 10, 0, 1, -36, -30, -36, -12, -6, 1, 77, 70, 91, 42, 21, 0, 1, -192, -184, -256, -152, -96, -24, -8, 1, 459, 450, 648, 432, 306, 108, 36, 0, 1, -1220, -1210, -1780, -1280, -1000, -460, -200, -40, -10, 1, 3201, 3190, 4741, 3542, 2926, 1540, 770, 220, 55, 0, 1
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Examples

			Triangle begins:
.1;
.-2,1;
.3,0,1;
.-8,-4,-4,1;
.15,10,10,0,1;
.-36,-30,-36,-12,-6,1;
.77,70,91,42,21,0,1;
.-192,-184,-256,-152,-96,-24,-8,1;
.459,450,648,432,306,108,36,0,1;
.-1220,-1210,-1780,-1280,-1000,-460,-200,-40,-10,1;
.3201,3190,4741,3542,2926,1540,770,220,55,0,1; ...
		

Crossrefs

Cf. A113287, A113289 (row sums), A113290 (-log), A072374.

Programs

  • PARI
    {T(n,k)=local(x=X+O(X^(n+2)),y=Y+O(Y^(n+2)),M=matrix(n+1,n+1,r,c, polcoeff(polcoeff(1/(1-x*y)+r*x/((1-x*y)*(1+x+x*y)),r-1,X),c-1,Y))); if(n
    				

Formula

T(n, 0) = (-1)^n*(n+1)*A072374(n-1) for n>=2, with T(1, 0)=-2, T(n, n)=1. T(n, 1) = (-1)^n*(n+1)*(A072374(n-1) - 1) for n>=2.

A113289 Row sums of triangle A113288.

Original entry on oeis.org

1, -1, 4, -15, 36, -119, 302, -911, 2440, -7199, 20186, -60359, 177204, -546615, 1683286, -5401759, 17456128, -58447151, 197925490, -691264279, 2446636396, -8897012871, 32811147054, -123933345455, 474792813176, -1858243857599, 7375013350282, -29840434526951
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Crossrefs

Showing 1-5 of 5 results.